Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Viable and fertile fruit flies in the absence of histone H3.3

13.11.2012
Histones – proteins that package DNA – affect cell function differently than previously assumed: the cell doesn’t need the histone H3.3 to read genes. Molecular biologists from the University of Zurich demonstrate that fruit flies can develop and reproduce in the absence of this histone. Additionally, cell division works without a histone modification previously deemed crucial.

Histones are proteins that are found in the cell’s nucleus, where they are present in complexes with DNA and are presumed to play a regulatory role in all processes that take place on the DNA. These processes include transcription, namely RNA synthesis, and the duplication of DNA during cell division.


Drosophila wing imaginal disc: Non-stained cells, areas in black, can not modify their histone H3 at the lysin. But the cells can divide and read genes. Dark blue represents non-mutant cells, cyan represents the modification at the lysin.

Picture: UZH

Until now, the function of the individual histones in the various processes could only be determined indirectly. Molecular biologists Konrad Basler and Martina Hödl from the University of Zurich for the first time directly studied the function of two histones and one histone modification – with surprising results: Viable and fertile organisms develop in the absence of the histone known as H3.3. Additionally a particular histone modification was believed to be crucial for the activation of gene transcription.

However, the researchers were able to demonstrate that this is also not the case. The established models for the role and function of histones and their modifications during the transcription and cell-division need to be revised.

Fertile fruit flies despite lack of histone H3.3

For their study, Basler and his postdoctoral student Hödl used the fruit fly Drosophila melanogaster, the genome of which has been fully decoded. In an initial experiment, the scientists switched the two histone variants H3.2 and H3.3 in the cells. In normal (i.e. non-manipulated) cells, histone H3.2 is only expressed in one specific phase of the cell cycle, the so-called S phase. Histone H3.3, however, is always expressed. Consequently, it was assumed that histone H3.3 plays a key role in transcription, especially in reading genes. Thus, the general consensus was that RNA synthesis would be restricted in the absence of histone H3.3. “In our experiment, under lab conditions viable and fertile fruit flies could develop from cells that do not have any H3.3,” explains Hödl, summing up the result that turns the previous understanding on its head. “Organisms also begin to develop from cells without H3.2 but these died in the first larval stage,” Hödl continues.

Genes are switched on and off without histone modification

Histones are modified by different enzymes at different points in the protein. In a second experiment, Basler and Hödl examined the importance of modifications of the fourth amino acid of the protein, a lysine. Modification of this lysine is thought to play a key role in activating and deactivating the transcription of the gene. To test this, the scientists replaced the lysine with non-modifiable amino acids in all the histone H3 genes. The result was another big surprise. “Cells without this specific histone modification are able to divide normally,” explains Basler before adding: “However, they do so considerably more slowly than cells that have not been modified.” Therefore, the modification of this lysine is not essential for the activation of the genes.

The results show that the activation of genes and the inheritance of the ability to activate genes work differently than previously assumed. Clearly, the structure of the transcription process is extremely robust. According to Basler, the role of this common histone modification for cell function has been overestimated in recent years.

Literature:
Martina Hödl, Konrad Basler, Transcription in the Absence of Histone H3.2 and H3K4 Methylation. Current Biology. November 8, 2012. http://dx.doi.org/10.1016/j.cub.2012.10.008
Contact:
Dr. Martina Hödl
Institute of Molecular Life Sciences
University of Zurich
Tel. +41 44 635 31 15
E-Mail martina.hoedl@imls.uzh.ch

Nathalie Huber | Universität Zürich
Further information:
http://www.uzh.ch

More articles from Life Sciences:

nachricht Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Lässt sich mit Boten-RNA das Immunsystem gegen Staphylococcus aureus scharf schalten?

Staphylococcus aureus ist aufgrund häufiger Resistenzen gegenüber vielen Antibiotika ein gefürchteter Erreger (MRSA) insbesondere bei Krankenhaus-Infektionen. Forscher des Paul-Ehrlich-Instituts haben immunologische Prozesse identifiziert, die eine erfolgreiche körpereigene, gegen den Erreger gerichtete Abwehr verhindern. Die Forscher konnten zeigen, dass sich durch Übertragung von Protein oder Boten-RNA (mRNA, messenger RNA) des Erregers auf Immunzellen die Immunantwort in Richtung einer aktiven Erregerabwehr verschieben lässt. Dies könnte für die Entwicklung eines wirksamen Impfstoffs bedeutsam sein. Darüber berichtet PLOS Pathogens in seiner Online-Ausgabe vom 25.05.2017.

Staphylococcus aureus (S. aureus) ist ein Bakterium, das bei weit über der Hälfte der Erwachsenen Haut und Schleimhäute besiedelt und dabei normalerweise keine...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: Orientierungslauf im Mikrokosmos

Physiker der Universität Würzburg können auf Knopfdruck einzelne Lichtteilchen erzeugen, die einander ähneln wie ein Ei dem anderen. Zwei neue Studien zeigen nun, welches Potenzial diese Methode hat.

Der Quantencomputer beflügelt seit Jahrzehnten die Phantasie der Wissenschaftler: Er beruht auf grundlegend anderen Phänomenen als ein herkömmlicher Rechner....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Tumult im trägen Elektronen-Dasein

Ein internationales Team von Physikern hat erstmals das Streuverhalten von Elektronen in einem nichtleitenden Material direkt beobachtet. Ihre Erkenntnisse könnten der Strahlungsmedizin zu Gute kommen.

Elektronen in nichtleitenden Materialien könnte man Trägheit nachsagen. In der Regel bleiben sie an ihren Plätzen, tief im Inneren eines solchen Atomverbunds....

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Meeresschutz im Fokus: Das IASS auf der UN-Ozean-Konferenz in New York vom 5.-9. Juni

24.05.2017 | Veranstaltungen

Diabetes Kongress in Hamburg beginnt heute: Rund 6000 Teilnehmer werden erwartet

24.05.2017 | Veranstaltungen

Wissensbuffet: „All you can eat – and learn”

24.05.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

DFG fördert 15 neue Sonderforschungsbereiche (SFB)

26.05.2017 | Förderungen Preise

Lässt sich mit Boten-RNA das Immunsystem gegen Staphylococcus aureus scharf schalten?

26.05.2017 | Biowissenschaften Chemie

Unglaublich formbar: Lesen lernen krempelt Gehirn selbst bei Erwachsenen tiefgreifend um

26.05.2017 | Gesellschaftswissenschaften